It still works for me. Does the problem survive a Firefox exit/restart cycle?

Occasionally there are keyboard shortcut conflicts with add-ons. It's not obvious to me how best to resolve these, but there are add-ons that let you change shortcuts; that might be useful if the conflict persists. To see whether it's caused by an extension, try Firefox's Safe Mode. That's a standard diagnostic tool to bypass interference by extensions (and some custom settings). More info: Troubleshoot Firefox issues using Safe Mode.

As suggested, I restarted the browser, and now it's back. I wasn't even able to use the Shift + F2 shortcut either, and the Tools-->Web Developer menu only had one entry beside "view source" and the option to get more tools. Now there's a huge list of tools all back again.

Is there anything I may have accidentally hit on the keyboard (or other) that could have disabled all those tools?

I think that the Web Developer menu is generated by some JavaScript at a later time (a lot of items are in a special #devtoolsKeyset keyset including the Web Console) as it doesn't seem to be there when Extensions are initialized.
So in your cause something went wrong and this script didn't run properly and failed to initialize the Web Developer menu.

Note that various Web Developer tools each have their own pref on the about:config page to enable or disable them.
You can search for devtools.*.enabled via the Search bar at the top of the about:config page.
Some are under development in the current release and thus disabled by default and will be enabled in future Firefox versions.